Switching Control Circuit Voltage Fluctuation Handling
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Solution Overview
Problem
Conventional switching control circuits fail to generate accurate control signals for switching devices when the high voltage side power supply fluctuates, leading to erroneous switching operations.
Innovation Solution
A switching control circuit comprising a control circuit, a setting circuit, a holding circuit, and a drive circuit that outputs appropriate logic levels for turning on and off a switching device, with a setting circuit that sets the logic level to a second logic level before receiving a set signal and a holding circuit that maintains this level, ensuring reliable operation even during voltage fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional control circuit is used to control switching devices, then the circuit structure is simple, but the control signal becomes erroneous when high voltage side power supply fluctuates
Solution Approach 1:
The setting circuit proactively sets the signal line to the second logic level before the reset signal is inputted, ensuring the holding circuit is prepared to maintain the correct state. This preliminary action prevents erroneous control signals from being generated when voltage fluctuations occur, as the system is already in the safe state before the fluctuation affects the control circuit.
Solution Approach 2:
The holding circuit acts as an intermediary between the control circuit and the switching device. It receives the control signal and maintains the logic level on the signal line independently of voltage fluctuations. This intermediary buffer ensures that even when the control circuit generates erroneous signals due to power supply instability, the holding circuit can maintain the correct logic level and prevent erroneous switching.
2Reliability
If no holding circuit is used, then the circuit complexity is reduced, but the control signal cannot be maintained during voltage fluctuations
Solution Approach 1:
The holding circuit provides beforehand cushioning by maintaining the logic level on the signal line during voltage fluctuations. It is designed to withstand and buffer against the harmful effects of power supply instability, ensuring that the control signal remains stable and accurate even when the high voltage side experiences fluctuations. This cushioning effect protects the switching device from erroneous control signals.
3Measurement precision
If the setting circuit sets the logic level before reset signal input, then control accuracy during voltage fluctuation is improved, but the circuit complexity increases
Solution Approach 1:
The setting circuit performs the action of setting the signal line to the second logic level before the reset signal is inputted to the control circuit. This timing is critical - it ensures that when voltage fluctuations occur and the control circuit might generate erroneous signals, the holding circuit is already prepared with the correct logic level to maintain on the signal line, thereby ensuring control accuracy without requiring complex real-time correction mechanisms.
Data Source
AI summary
A switching control circuit that controls switching of a switching device of a bridge circuit for driving a load. The switching control circuit includes a control circuit that outputs, on a signal line, a control signal at first and second logic levels for turning on and off the switching device based on a set signal and a reset signal, respectively, a setting circuit that is connected to the signal line, and that sets the logic level of the signal line to the second logic level for a period after the reset signal is inputted to the control circuit and before the set signal is inputted to the control circuit, a holding circuit that is connected to the signal line, and that holds the logic level of the signal line, and a drive circuit that is connected to the holding circuit, and that drives the switching device based on the output of the holding circuit.